Example of Unit Testing without SUT

UnitTestingWithoutSUT.swift

   func test_load_shouldRespondSomething() {
        let analytic: Inalytic = AnalayticSpy()
        let storageClient: IUserDefaults = UserDefaultsSpy()
        let serviceClient: IHTTPClient = HTTPClientSpy()
        let storage: TextToSpeechPreferencesStorage = TextToSpeechPreferencesStorageImpl(client: storageClient)
        let service: TextToSpeechPreferencesService = TextToSpeechPreferencesServiceImpl(client: serviceClient)
        let repository: TextToSpeechPreferencesRepository = TextToSpeechPreferencesRepositoryImpl(
            storage: storage,
            service: service
        )
        let useCase: LoadLanguageIdPreferencesUseCase = LoadLanguageIdPreferencesUseCaseImpl(
            repository: repository,
            analytic: analytic
        )

        // ...
        // other code
        
        XCTAssertNotNil(useCase)
    }